The United States is engaged in an important debate about whether commercial insurers should be required to pay for longer postpartum stays. Supporters of the mandate contend that it is necessary to protect the health and safety of mothers and their newborns, that it will save money by reducing the number of readmissions, and that it is "the right thing to do." Critics respond that there is no convincing evidence that early discharge represents an excessive danger to mothers and newborns, and that the same amount of resources applied to other health measures would produce more health at a lower cost. The purpose of this study is to evaluate the costs and health consequences of mandates requiring insurers to pay for a minimum 48-hours hospital stay for mothers and newborns after a vaginal delivery or 96 hours following a Cesarean section. To evaluate the efficacy of this mandate, three related policy questions are addressed. First, what are the health benefits of the mandate? Second, how much does the mandate cost? And, third, is the mandate cost-effective? I propose to answer these questions using a data set from the Management and Outcomes of Childbirth PORT. This data set contains an extremely rich array of clinical, sociodemographic, insurance, hospital, physician and charge variables for every birth in Washington state in 1989 and 1990. It contains 159,311 total records, of which 133,589 records have perfect matches between hospital discharge records and birth certificate records. Health benefits will be estimated by assessing the relationship between length of postpartum stay and the readmission rate. Costs will be estimated using the ratio of cost to charges method based on hospital- level data from the Medicare Cost Reports. The final results will inform policymakers in Washington and in other states where the mandate is being considered.